The present invention relates to the field of otology implants and is particularly directed toward a myringotomy tube.
Since about 1952 myringotomy tubes (also referred to as tympanotomy tubes) have been used as a form of treatment for recurrent infections in the ear and for abnormal pressure and fluid in the middle ear behind the eardrum due to abnormal ventilation of the middle ear. The purpose of any myringotomy tube is to maintain a connection between the external auditory canal and the middle ear space. This allows for ventilation of the middle ear space with air, and for the evacuation of purulent material and fluid from the middle ear space. More than two million operations are performed yearly in the United States wherein these tubes are surgically inserted into the ear drum (tympanic membrane) so as to provide fluid communication between the middle ear and the external canal.
Myringotomy tubes typically stay in the ear drum for four to thirty-six months, depending upon the age of the patient and the shape of the tube. Most patients in the younger age groups (1-6 years) require a myringotomy tube for twelve to twenty-four months. Older patients may require very short term tubes (1-3 months) or long term tubes (2-3 years) depending upon their etiology of their otologic dysfunction.
The ideal myringotomy tube would stay in place indefinitely without extruding, but would instantly be gone from the ear when the patient no longer needed ventilation of the middle ear. Numerous designs have been developed which allow myringotomy tubes to stay in position for long periods (at least 1 year or more) without extruding. Unfortunately, many of these tubes never extrude and must be surgically removed. This removal risks injury to the surrounding ear drum and any middle ear structures which may have connected to the tube by fibrous adhesions in the middle ear. In addition, this procedure must be done under anesthesia on children who do not tolerate such manipulation in the clinic or office setting. Furthermore, myringotomy tubes that do not extrude after twenty-four months very often cause a permanent perforation of the ear drum after they are surgically removed. This perforation must be surgically repaired.
Other myringotomy tubes have been designed to avoid the problem of myringotomy tubes staying in place longer than desired (2-3 years or more). Unfortunately, by the nature of their design, these tubes extrude easily and often extrude during the first four months after placement. This premature extrusion results in recurrent disease and usually results in the myringotomy tube having to be replaced in the ear drum. Again, in children, this requires another operating room procedure.
The present invention solves the problems noted above associated with existing myringotomy tubes.
The present invention relates to a bioerodable myringotomy tube.
The invention is to be made of various forms of collagen, which is a natural architectural component of the tissues of the human body. Gelatin is a variation of collagen that is prepared and manufactured in various ways. The invention, in its preferred form, is to be made of a form of gelatin called GELFILM(copyright). In other forms, the invention is to be made of other forms of collagen and gelatin, not specifically GELFILM(copyright).
In one embodiment of the present invention, there is provided a myringotomy tube for providing drainage of the middle ear through the external ear canal. The myringotomy tube is comprised of a member having a passageway provided therein for communicating the middle ear with the external ear canal subsequent to the member having been inserted through a surgical incision in the tympanic membrane. The myringotomy tube is further comprised of a bio erodable material so as to dissolve upon exposure to middle ear fluids, whereby the myringotomy tube does not have to be surgically removed from the tympanic membrane.
In one embodiment, the bio erodable material dissolves over a period of nine to twelve months.
In a preferred embodiment, the myringotomy tube is made from GELFILM(copyright). GELFILM(copyright) has a long half-life (approximately one year when used in the middle ear).
In still another embodiment, the myringotomy tube might be made of GELFILM(copyright) which is impregnated with various broad spectrum antibiotics so as to assist in the treatment of infection or disease in the ear. As the tube dissolves, the antibiotic is released, aiding in the prevention of infections in the middle ear.
In another embodiment, the myringotomy tube might be made of forms of gelatin other than GELFILM(copyright).
In still another embodiment, the myringotomy tube might be made of collagen that is not in the form of a gelatin or GELFILM(copyright).
In still another embodiment, the myringotomy tube might be made of gelatin other than GELFILM(copyright) which is impregnated with various broad spectrum antibiotics.
In still another embodiment, the myringotomy tube might be made of collagen that is not in the form of a gelatin or GELFILM(copyright) and which is impregnated with various broad spectrum antibiotics.
For a standard, non-dissolvable myringotomy tube, the connection between the middle ear space and the external canal is maintained until such time as the tube dislodges from the tympanic membrane and migrates out of a functional position. On the other hand, for a dissolvable myringotomy tube, additional structural considerations must be taken into account. A dissolvable tube dissolves over a period of time thus causing a potential change to the size and patency of the inner lumen of the tube. As a tube is not functional when the lumen patency is lost, not maintaining the tubes opening becomes a continuous threat to the effectiveness of a dissolvable tube once the tube is exposed to bodily fluids that result in the tube""s dissolution.
Applicant has found that as the collagen myringotomy tube dissolves, the shaft tends to lose its lumen patency and collapse upon itself if the internal diameter is not made large enough. Premature collapse of the tube blocks the passageway and prevents proper drainage of the middle ear. Therefore, in yet another embodiment of the invention, the passageway of the shaft has an internal diameter of at least about 2.0 mm. Applicant has discovered that the passageway must have an internal diameter of at least about 2.0 mm in order to prevent premature collapse of the shaft as the collagen dissolves. Passageways with internal diameters less than 2.0 mm tend to collapse upon themselves thereby blocking the passageway and rendering the tube non-functional.
It is a purpose of a preferred embodiment of the present invention, to provide a myringotomy tube which further provides for long term stability in the ear drum, without premature extrusion.
A bio erodable or dissolvable myringotomy tube avoids many of the problems associated with standard non-dissolvable tubes.
These and various other advantages and features of novelty which characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the accompanying drawings and descriptive matter, which form a further part hereof, and in which there is illustrated and described a preferred embodiment of the invention.